Create a new group “foo” with one static host. Nodes type and address are ordered.

ins group after /files/etc/dhcp3/dhcpd.conf/subnet[network='172.16.0.0']/*[last()]
set /files/etc/dhcp3/dhcpd.conf/subnet[network='172.16.0.0']/group[last()]/host foo
set /files/etc/dhcp3/dhcpd.conf/subnet[network='172.16.0.0']/group[host='foo']/host/hardware/type "ethernet"
set /files/etc/dhcp3/dhcpd.conf/subnet[network='172.16.0.0']/group[host='foo']/host/hardware/address "00:00:00:aa:bb:cc"
set /files/etc/dhcp3/dhcpd.conf/subnet[network='172.16.0.0']/group[host='foo']/host/fixed-address 172.16.0.100